Sarah Michelle Gellar has opened up about her least favourite season of Buffy the Vampire Slayer.

As part of EW's extensive 20th anniversary celebration, she revealed that season six marked the low point of the show for her, both because of what happened with Buffy and a lack of contact with creator Joss Whedon.

Season six marked the show's move from The WB to UPN and came after Buffy seemingly died in the season five finale. Whedon also stepped away from showrunner duties, but remained an executive producer, with Marti Noxon taking over.

It led to a darker tone as Tara was killed and Willow was set on a path to vengeance as Dark Willow. It also saw Buffy almost getting raped by Spike.

Then again, it did have the brilliant 'Once More, With Feeling'...

"I've always said that season 6 was not my favourite. I felt it betrayed who she was. Even just getting to talk to Joss and be able to get his opinion was not as easy when he's not upstairs," Gellar explained.

"He had three shows. He had Angel and Firefly so that was hard. But he made sure to dedicate the time to season 7 and that was his promise to me: that we would right all the wrongs and he kept that promise."

However, Whedon has a completely different view on season six compared to his lead star. "I love season 6. Marti and I wanted to talk about an unhealthy relationship. It was borderline abusive until it actually became abusive," he explained.

"It was on both sides. It wasn't just that she was with someone dark – she found the darkness within herself. This has to do with the consequences of power."